1. Field of the Invention
The present invention is directed to an air supply apparatus for regulating the temperature and humidity of air and for supplying the air to semiconductor device fabricating equipment.
2. Description of the Related Art
Generally, semiconductor devices are fabricated through many processes. In particular, a photolithographic process for forming required patterns is essential to the fabricating of semiconductor devices. A first step of the photolithographic process is to coat a wafer with a photoresist. This coating step is conducted by a coater unit. A very significant aspect of the coating step is the uniformity in thickness of the photoresist. The environment within the coater unit is critical to the degree to which the thickness of the coating of photoresist can be made uniform.
A typical coater unit has an air supply apparatus for automatically controlling the temperature and humidity within a coating chamber. Referring to FIG. 1, a conventional air supply apparatus 10 includes an electronic temperature/humidity controller (THC) 12, an ultra-pure water pipe 16 through which ultra-pure water from an ultra-pure water source 14 is delivered to the THC 12, and an air pipe 18 through which air is delivered to the semiconductor device fabricating equipment 20. The temperature/humidity controller (THC) regulates the temperature and humidity of the air to provide an optimum environment within a coating chamber of the semiconductor device fabricating equipment 20.
The inside of the ultra-pure water pipe 16a is periodically cleaned and sterilized to rid the ultra-pure water pipe 16 of microbes, such as bacteria. The cleaning of the ultra-pure water pipe 16 is conducted for a predetermined amount of time, e.g., 24 hours. The delivering of the ultra-pure water to the THC 12 is stopped during the cleaning of the ultra-pure water pipe 16, i.e., the air supply apparatus 10 is shut down.
An object of the present invention is to provide an air supply apparatus by which ultra-pure water can be supplied to a temperature/humidity controller even while an ultra-pure water pipe is being cleaned.
According to one aspect of the present invention, an air supply apparatus for use with semiconductor device fabricating equipment includes an ultra-pure water source, a buffer tank, an ultra-pure water pipe for delivering ultra-pure water to the buffer tank from the ultra-pure water source, a temperature/humidity controller that receives ultra-pure water from the buffer tank, an air pipe for providing temperature- and humidity-conditioned air from the temperature/humidity controller to the semiconductor device fabricating equipment, and control means for allowing the apparatus to be operated in both a normal mode and a cleaning mode in which the temperature/humidity controller receives ultra-pure water.
The control means preferably comprises at least one valve disposed in the piping of the air supply apparatus, such as in the ultra-pure water pipe, and a change switch for controlling the opening/closing of the valve(s).
The air supply apparatus may further include a nitrogen supply pipe connecting a source of nitrogen to the buffer tank so as to provide pressure that forces the ultra-pure water from the buffer tank to the temperature/humidity controller during the cleaning mode. An exhaust pipe is connected to the buffer tank for allowing the nitrogen gas to be exhausted from the buffer tank once the normal mode resumes. In this case, the control means also includes valves disposed in the exhaust pipe and the nitrogen supply pipe, respectively.
Sensors may also be provided for sensing the level of the ultra-pure water in the buffer tank.